F150 SHIFT LEVER LINKAGE PROBLEM.

I believe that the cable is broken on the shift lever linkage for my 1993 Ford F-150 truck(4x4/extended cab/automatic), but i'm not sure. I can pull my shift lever back, but I can't shift down into any of the gears. The shift lever just wiggles loosely back and forth and I can see at the end of the lever a small arm with a thin cable attached to it. How can I fix this problem?